地下综合管廊电缆火灾温度场分布及烟气流动特性分析

发布时间：2018-06-09 17:20

本文选题：地下综合管廊 + 电缆　；参考：《中国矿业大学》2017年硕士论文

【摘要】：随着我国经济的快速发展,地下综合管廊成为了国家“十三五”规划的重要城市基础设施之一。火灾是地下综合管廊面临的最大安全风险之一。由于空间狭小,通风受限,综合管廊一旦发生火灾,热烟气难以及时排出,管廊内温度急剧上升,将引燃管廊内的电力、通讯电缆和其它管道的保温材料,造成严重经济损失,甚至导致城市瘫痪。电缆起火是综合管廊火灾的常见原因。本文通过开展YZ型橡套电缆燃烧特性试验,分析了电缆护套材料的燃烧热值及外部辐射热流下热解特征。实验测得YZ电缆橡胶护套材料燃烧热值为11 308.5 kJ/kg,紧密排布和间歇排情况下,其临界辐射热流分别为24.75 kW/m2、27.40 kW/m2。搭建1:3.6缩尺寸综合管廊模型,开展火灾模型实验。发现地下综合管廊电缆火灾在200 s-600 s期间燃烧较为剧烈,该阶段仅占燃烧时间的23%,却贡献了75%的质量损失。根据质量损失速率计算得缩尺寸模型实验中1#、2#、3#火源燃烧旺盛阶段对应的平均热释放速率分别为34.19 kW、24.06 kW、17.19 kW。根据相似原理计算得到全尺寸火灾中1#、2#、3#火源平均热释放速率分别为533.02kW、375.09 kW、279.06 kW。模型实验结果表明:管廊顶棚下方最高温升仅与火源距顶棚的距离和无量纲释热速率有关;顶棚温度沿纵向呈指数规律衰减。对实验数据进行整合分析,给出了管廊顶棚下方最高温升模型和顶棚纵向温度分布模型。对缩尺寸模型开展火灾数值模拟研究,模拟结果表明其顶棚最高温升、纵向温度分布规律与实验数据基本吻合,从而验证了FDS火灾模拟软件在研究地下综合管廊火灾方面的可行性。针对沈阳某地下综合管廊建立全尺寸数值模拟模型,采用FDS研究不同纵向风速对温度场分布及烟气流动特性规律的影响。研究发现纵向温度在烟气逆流前锋处有突然跃升现象,下风侧顶棚温度场纵向衰减有类似指数规律。观察数值模拟现象并结合理论分析,得到无量纲烟气逆流长度与无量纲火源功率以及无量纲风速之间关系。对模拟数据进行处理提出了地下综合管廊火灾烟气逆流长度预测模型。根据前人研究理论结合经验公式计算值,得到无量纲纵向临界风速与无量纲火源功率之间关系。经过无量纲分析,提出了无量纲临界风速预测模型。
[Abstract]:With the rapid economic development of our country, the underground comprehensive pipe corridor has become one of the important urban infrastructure in the 13th Five-Year Plan. Fire is one of the biggest safety risks faced by underground plumbing. Because of the narrow space and limited ventilation, once the fire occurs in the integrated pipe gallery, the hot smoke is difficult to be discharged in time, and the temperature in the pipe gallery rises sharply. The heat preservation material of the electric power, communication cable and other pipes in the pipe gallery will be ignited, resulting in serious economic losses. It even paralyzes the city. The fire of cable is the common cause of fire in integrated pipe gallery. In this paper, the combustion calorific value of the cable sheath material and the pyrolysis characteristics under the external radiant heat flow are analyzed through the test of the combustion characteristics of the YZ type rubber sheathed cable. The experimental results show that the combustion calorific value of YZ cable rubber sheathing material is 11 308.5 KJ / kg, and the critical radiation heat flux is 24.75 kW / m227.40 kW / m2 under the condition of tight arrangement and intermittent discharge, respectively. The model of 1: 3.6 condensed pipe gallery was built and the fire model experiment was carried out. It is found that the underground integrated pipe gallery cable fire burns intensely during the period of 200s-600 s, which only accounts for 23% of the burning time, but contributes 75% of the mass loss. According to the mass loss rate, the average heat release rate corresponding to the burning exuberant stage of 1 #Li 2 #4 is 34.19 kW / t 24.06 kW / m 17.19 kW, respectively. According to the principle of similarity, the average heat release rate of 1 #an 2 #HG fire source in a full-scale fire was calculated to be 533.02 kW ~ 375.09 kW ~ (-1) 279.06 kW, respectively. The results of model experiments show that the maximum temperature rise under the roof of the pipe gallery is only related to the distance from the fire source to the roof and the dimensionless heat release rate, and the temperature of the roof decreases exponentially along the longitudinal direction. Based on the analysis of the experimental data, the maximum temperature rise model and the vertical temperature distribution model are given. The fire numerical simulation of the shrinking size model is carried out. The simulation results show that the maximum temperature rise of the ceiling and the longitudinal temperature distribution are in good agreement with the experimental data. Thus, the feasibility of FDS fire simulation software in the study of underground integrated pipe gallery fire is verified. A full-scale numerical simulation model was established for an underground integrated pipe gallery in Shenyang. FDS was used to study the influence of different longitudinal wind speeds on temperature field distribution and flue gas flow characteristics. It is found that the vertical temperature jumps suddenly at the front of the flue gas countercurrent, and the vertical attenuation of the temperature field in the downwind side has a similar exponential law. By observing the numerical simulation phenomenon and combining with the theoretical analysis, the relationship between the countercurrent length of the dimensionless flue gas and the dimensionless fire source power and the dimensionless wind speed is obtained. A prediction model of smoke countercurrent length in underground integrated pipe gallery fire is proposed for the simulation data processing. The relationship between dimensionless longitudinal critical wind speed and dimensionless fire source power is obtained according to previous research theory and empirical formula. After dimensionless analysis, a dimensionless critical wind speed prediction model is proposed.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU990.3;TU998.1

【参考文献】